/*********************************************************************************
 *      Copyright:  (C) 2025 LingYun<iot25@lingyun>
 *                  All rights reserved.
 *
 *       Filename:  poll.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(11/03/25)
 *         Author:  LingYun <iot25@lingyun>
 *      ChangeLog:  1, Release initial version on "11/03/25 20:56:48"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>
#include <pthread.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <poll.h>

#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))

static inline void print_usage(char *progname);
int socket_server_init(char *listen_ip, int listen_port);

int main(int argc, char **argv)
{
	int listenfd, connfd;
	int serv_port = 0;
	int daemon_run = 0;
	char *progname = NULL;
	int opt;
	int rv;
	int i, j;
	int found;
	int max;
	char buf[1024];
	struct pollfd fds_array[1024];
	struct option long_options[] =
	{ 
		{"daemon", no_argument, NULL, 'b'},
		{"port", required_argument, NULL, 'p'},
		{"help", no_argument, NULL, 'h'},
		{NULL, 0, NULL, 0}
	}; 
	progname = basename(argv[0]);
	/*  Parser the command line parameters */
	while ((opt = getopt_long(argc, argv, "bp:h", long_options, NULL)) != -1)
	{ 
		switch (opt)
		{ 
			case 'b':
				daemon_run=1;
				break;
			case 'p':
				serv_port = atoi(optarg);
				break;
			case 'h': /*  Get help information */
				print_usage(progname);
				return EXIT_SUCCESS;
			default:
				break;
		} 
	} 
	if( !serv_port )
	{ 
		print_usage(progname);
		return -1;
	}
	if( (listenfd=socket_server_init(NULL, serv_port)) < 0 )
	{
		printf("ERROR: %s server listen on port %d failure\n", argv[0],serv_port);
		return -2;
	}
	printf("%s server start to listen on port %d\n", argv[0],serv_port);
	/*  set program running on background */
	if( daemon_run )
	{
		daemon(0, 0);
	}
	for(i=0; i<ARRAY_SIZE(fds_array) ; i++)
	{
		fds_array[i].fd=-1;
	}
	fds_array[0].fd = listenfd;
	fds_array[0].events = POLLIN;
	max = 0;

	for ( ; ; )
	{
		/*  program will blocked here */
		rv = poll(fds_array, max+1, -1);
		if(rv < 0)
		{
			printf("select failure: %s\n", strerror(errno));
			break;
		}
		else if(rv == 0)
		{
			printf("select get timeout\n");
			continue;
		}

		/*  listen socket get event means new client start connect now */
		if (fds_array[0].revents & POLLIN)
		{
			if( (connfd=accept(listenfd, (struct sockaddr *)NULL, NULL)) < 0)
			{
				printf("accept new client failure: %s\n", strerror(errno));
				continue;
			}
			found = 0;
			for(i=1; i<ARRAY_SIZE(fds_array) ; i++)
			{
				if( fds_array[i].fd < 0 )
				{
					printf("accept new client[%d] and add it into array\n", connfd );
					fds_array[i].fd = connfd;
					fds_array[i].events = POLLIN;
					found = 1;
					break;
				}
			}

			if( !found )
			{
				printf("accept new client[%d] but full, so refuse it\n", connfd);
				close(connfd);
				continue;
			}

			max = i>max ? i : max;
			if (--rv <= 0)
				continue;
		}
		else/*  data arrive from already connected client */
		{
			for(i=1; i<ARRAY_SIZE(fds_array); i++)
			{
				if( fds_array[i].fd < 0)
					continue;
				if( (rv = read(fds_array[i].fd, buf, sizeof(buf)))<= 0)
				{
					printf("socket[%d] read failure or get disconncet.\n",fds_array[i].fd);
					close(fds_array[i].fd);
					fds_array[i].fd = -1;
				}
				else
				{
					printf("socket[%d] read get %d bytes data\n",fds_array[i].fd,rv);
					
					/* convert letter from lowercase to uppercase */
					for(j=0; j<rv; j++)
						buf[j]=toupper(buf[j]);

					if( write (fds_array[i].fd, buf, rv)< 0)
					{
						printf("socket[%d] write failure :%s\n",fds_array[i].fd, strerror(errno));
						close(fds_array[i].fd);
						fds_array[i].fd =-1;
					}
				}
			}
		}
	}
CleanUp:
	close(listenfd);
	return 0;
}


static inline void print_usage(char *progname)
{
	printf("Usage: %s [OPTION]...\n",progname);

	printf(" %s is a socket server progname, which used to verify client and echo back  string from it\n",progname);
	printf("\nMandatory arguments to long options are mandatory for short options too:\n");

	printf(" -b[daemon] set program running on background\n");
	printf(" -p[port] Socket server port address\n");
	printf(" -h[help ] Dispaly this help information \n");

	printf("\nExample: %s -b -p 8900\n",progname);
	return ;
}

int socket_server_init(char *listen_ip,int listen_port)
{
	struct sockaddr_in			servaddr;
	int							rv = 0;
	int							on = 1;
	int							listenfd;

	if( (listenfd = socket(AF_INET, SOCK_STREAM, 0))< 0)
	{
		printf("Use socket() to create a TCP socket failure: %s \n",strerror(errno));
		return -1;
	}

	/*  Set socket port reseable, fix 'Address already in use ' bug when socket server restart */
	setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(listen_port);

	if( !listen_ip )/* Listen all the local IP address */
	{
		servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	}
	else/* listen the specified IP address */
	{
		if(inet_pton(AF_INET,listen_ip, &servaddr.sin_addr) <=0)
		{
			printf("inet_pton() set listen IP address failure\n");
			rv = -2;
			goto CleanUp;
		}
	}

	if(bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr))< 0)
	{
		printf("Use bind() to bind the TCP socket failure: %s\n",strerror(errno));
		rv =-3;
		goto CleanUp;
	}

	if(listen(listenfd, 13) < 0)
	{
		printf("Use bind() to the TCP socket failure: %s\n", strerror(errno));
		rv = -4;
		goto CleanUp;
	}
CleanUp:
	if(rv<0)
		close(listenfd);
	else
		rv = listenfd;

	return rv;
}

